1. Field of the Invention
The present invention relates to corneal implants and to a method of delivering and securing corneal implants in fluid-flow limiting relation to the posterior cornea, such as to treat corneal edema, including removably securing the corneal implant.
2. Description of the Related Art
Excess corneal fluid, also known as corneal edema, is a painful condition caused by an accumulation of fluid within the cornea that can lead to loss of corneal clarity and visual acuity. Corneal edema is most often the result of a decreased number or decreased function of the corneal endothelial cells that form a monolayer lining the inside, or posterior, side of the cornea. For example, the endothelial cells can fail to adequately pump aqueous fluid that diffuses into the cornea from the anterior chamber out of the cornea and back into the anterior chamber.
Current treatment for corneal edema includes medical treatment and therapy to dehydrate the cornea with hypertonic saline, and in some cases, corneal transplant. There are approximately 50,000 corneal transplants performed each year in the United States, with similar statistics for Europe. The three major indications for corneal transplant are Fuchs' dystrophy, pseudophakic bullous edema, and corneal transplant rejection. Corneal transplants in the United States and abroad are limited, however, by tissue accessibility, surgical cost, long patient recovery time, changes in refraction affecting vision, availability of corneal specialists, and the risk of transplant rejection or failure, which can be in the range of 10-30%.
Corneal implants have been developed to treat edema while attempting to avoid some of the problems of transplant surgery. For instance, synthetic corneal implants can be used in place of tissue, thereby obviating issues of tissue availability and limiting the possibility of host rejection. However, there are still no acceptable ways of inserting and securing the corneal implants to the eye of a patient that will minimize interference with visual acuity and damage to the eye. For example, some known methods involve suturing the implant to the cornea, or applying a bonding agent to permanently bond the implant to the cornea. However, suturing the implant creates scar tissue, which can interfere with vision, and may be rejected by the patient's body. Bonding agents may cause chemical damage to the cornea or implant over time, and also may affect vision. Moreover, known corneal implants and methods only permit permanent attachment of the corneal implant, and may even preclude future corneal transplants.
Accordingly, it would be beneficial to have a method of inserting and securing a corneal implant to the cornea that does not interfere with vision, and possibly could even correct vision simultaneously with treating corneal edema. In addition, it would also be beneficial to have a method of inserting a corneal implant such that it can later be removed if necessary, such as for a replacement or if the patient's condition subsides.